1. Field of the Invention
This invention relates to a dry-type analytical element suitable for measuring the enzyme activity of a liquid sample, particularly a biological body fluid.
2. Description of the Prior Art
A known dry-type analytical element for measuring lactate dehydrogenase (LDH) contains lactic acid or its salt and nicotinamide adenine dinucleotide coenzyme (NAD.sup.+) of the oxidized form in its water-permeable layer and nicotinamide adenine dinucleotide coenzyme of reduced form (NADH) is detected by a coloring reagent or the like. Such an analytical element for LDH activity assey is disclosed in Japanese patent KOKAI 59-88097, etc., and it is suitable for measuring the LDH activity of a liquid sample. In such analytical elements, the density of the background sometimes increases during the handling required for measurement, and as a result, the calibration curve previously prepared cannot be utilized. This phenomenon was remarkable, when polyvinylpyrrolidone known as the stabiliser and NAD.sup.+ (Japanese Patent KOKOKU 49-27717) was added to the water-permeable layer containing NAD.sup.+ as the binder.